Technical Abstract:
Two chicken cytokine genes homologous to mammalian IL-16 and IL-17 were identified from a chicken intestinal EST library and their biological properties were characterized. Chicken intestinal EST library was prepared from the intestinal IELs of Eimeria-infected chickens. Chicken IL-16 is predicted to be consisted of 607 amino acids and showed 86% sequence identity to duck IL-16, and 49 - 52% identity to various mammalian homologues. IL-16 mRNA were identified in several chicken lymphoid tissues but none of the non-lymphoid tissues examined. A recombinant chicken IL-16 protein which was expressed in COS-7 cells displayed chemoattractant activity for splenic lymphocytes. Chicken IL-17 contained a 507 bp open reading frame and is predicted to encode a protein of 169 amino acids with a molecular mass of 18.9 kDa which includes a 27 residue NH2-terminal signal peptide, a single potential N-linked glycosylation site, and 6 cysteine residues conserved with mammalian IL-17s. IL-17 shared 37 - 46% amino acid sequence identity to the previously described mammalian homologues and contained sequences homologous to the open reading frame of HVS 13. IL-17 transcripts were identified in a REV-transformed chicken CU205 cell line and Con A-stimulated splenic lymphocytes but not in normal tissues. Supernatant of COS-7 cells transfected with chicken IL-17 cDNA induced IL-6 production by chicken embryonic fibroblasts.